The Darling family were prominent pioneers, business people, and politicians in the Thousand Islands Region in Ontario during the nineteenth and early twentieth centuries.

Thomas Darling (1813-1882/ [1814-1883?]) and his wife Janet Findlay (1825-1906) came to the area from Berwick, Scotland in 1837. Mr. Darling began a cordwood business in 1837, supplying wood to steamers traveling along the St. Lawrence River.

In 1845, following the success of his cordwood business, Darling opened a general store at Darlingside on the St. Lawrence River. It was closely associated in a barter-and-credit system of trade with the wood business.

From the 1845 census, it is evident that at that time the Darling family only consisted of Thomas and Janet Darling. Eventually, they had ten children. Two of the eldest boys died at very young ages. Each of the Darling children was unique and, to some, eccentric. The Darling girls were well educated. Each boy, with the exception of Arthur Darling, was also extensively involved in the community. The family exercised considerable power in the community because of their economic status. Some of the Darling men held public offices. The family were staunch Presbyterians and active in the support of the church in Lansdowne.

A second store was established in 1871, staffed by Darling's oldest son, John. In 1883 Thomas Darling died and was survived by three sons - John David William, Thomas John and George Henry - who carried on the family business with some diversification. Thomas and John continued in the store while George specialized in imported teas he sold through travelling agents. There are no records of the sale of wood after 1883. Beside their commerce, the family owned and managed considerable property in the St. Lawrence and in the early twentieth century purchased and mortgaged property in Alberta.

The majority of the family is buried in Lansdowne Cemetery. The Darling family used Darlingside as a summer home from the 1940s until its sale in 1995.

The quartz mine was located on lot eight in the ninth concession of Lansdowne (near Black Rapids on Red Horse Lake).
The first mine was dug by Arza Sherman in 1897, who mined quartz and attempted to sell it in the United States. The mine was essentially a hole in the ground with wooden ladders to descend. Sherman sold the property to John Moorehead in 1901.

In 1938, Loris McElroy picked up samples from the site, showed them to a chance acquaintance named George Moroughan, who in turn showed them to Jack Steele, the owner of a mica mine near Sydenham.
In July 1942, the three men signed an agreement to create the Red Horse Lake Mining Syndicate, dividing profits from the mine equally. They also mined quartz, because of its utility in technologies such as radio frequency control and bomb sights (and worth a reported $3000 per ton due to the war effort).

In 1943, the Red Horse Lake Mining Syndicate gave way to the Rare Minerals Prospecting Syndicate which conducted considerable exploration, before giving way in turn to Quartz-Crystals Mining Corporation of Canada Limited. Both the syndicates and the Mining Corporation sold quartz to the Canadian government. The Mining Corporation operated the mine until it went bankrupt in 1950.

In 1951, a new company funded by the federal government, Quartz Crystals Mines Limited, mined the quartz crystals, employing six to seven men until the government announced in 1954 that stockpiles were sufficient and closed the mine.